QUESTION: A 51-year-old male, who sustained a partial tear of the proximal right adductor longus tendon at work, was evaluated. A magnetic resonance imaging (MRI) scan obtained 3 days post-injury showed a tear of approximately 10% of the tendon with surrounding edema. He was treated with platelet-rich plasma (PRP) injections. No repeat MRI was obtained when the patient was deemed at maximum medical improvement (MMI) one-year post-injury. Using the fifth edition of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), which is applicable in the patient's state, his treating physician, despite the patient having normal hip adduction strength, provided a rating based on strength loss, using half the impairment that would be assigned for 4/5 hip adduction weakness and pain. During a subsequent independent medical evaluation, the patient complained of pain and weakness with prolonged walking but was otherwise asymptomatic. Physical examination was normal including no tenderness, grade 5/5 hip adduction strength without pain on manual muscle testing, full hip abduction, and normal gait. What is the correct impairment rating?ANSWER: Section 2.3, Examiners’ Roles and Responsibilities, states, “The physician's role in performing an impairment evaluation is to provide an independent, unbiased assessment of the individual's medical condition, including its effect on function, and identify abilities and limitations to performing activities of daily living as listed in Table 1-2” (5th ed, 18). A treating physician has an inherent advocacy role for the patient and therefore by definition cannot be “independent” and “unbiased.”The process of assessing lower extremity permanent impairment is described in Chapter 17, The Lower Extremities (5th ed, 523-564). Thirteen methods can be used to assess the lower extremities. A cross-usage chart (Table 17-2, 5th ed, 526) indicates which methods and resulting impairment ratings may be combined.In Section 17.2d, Muscle Atrophy (Unilateral), the AMA Guides advises:Section 17.2e, Manual Muscle Testing, explains the validity of muscle testing:In this case, strength was normal, ie, grade 5/5, without pain on resisted adduction. Had there been pain on manual muscle testing, strength would be invalidated as a rating method. The patient did report pain and weakness with prolonged walking, but the AMA Guides does not rate endurance.It is also important to assess the reliability of the subjective information presented. The premise that examinee reports are accurate has repeatedly failed scientific testing, as detailed in the September/October 2009 issue of the AMA Guides Newsletter.1 Impairment evaluations are vulnerable to being influenced by the examinee's self-reported history. Studies have demonstrated that claimants tend to over-report symptoms and functional difficulties.Lacking other information, it is difficult to determine whether the reported symptoms with prolonged walking are valid. However, given the tear this is possible. Yet many athletes sustain tendon and muscle strains (ie, tears detected by MRI) and are temporarily disabled from their sports but return to play without sequela.Impairment is defined as “a loss, loss of use, or derangement of any body part, organ system, or organ function” (5th ed, 601). The patient had objective evidence of impairment on the MRI scan, ie, the partial tendon tear. The question is whether that impairment became permanent. He reports pain and weakness with prolonged walking. However, there is no subjective or objective evidence of permanent impairment on physical examination. Because no repeat MRI scan was obtained at MMI, it is unknown for certain whether the partial tear healed completely, partially, or not at all. So, is there permanent impairment? Some would maintain that given the normal physical examination at MMI, there is no ratable impairment using the fifth edition. Others, such as the treating physician in this case, might point out the patient's limited complaints at MMI are not indicative of symptom magnification and probably credible, implying some residual derangement. If asked to assume the latter is true, how does one rate the impairment with the fifth edition? In Section 1.5, Incorporating Science with Clinical Judgment, the AMA Guides states:A partial tear of adductor tendon is an “unlisted condition” in the fifth edition. There is no diagnosis-based means to rate the patient because Table 17-33, Impairment Estimates for Certain Lower Extremity Impairments (5th ed, 546), does not list adductor longus tear.In this case, there is also no “measurable impairment.” Even if there was, eg, residual hip adduction weakness, Table 17-8, Impairment Due to Lower Extremity Muscle Weakness (5th ed, 532), does not list a rating for same, just weakness on abduction, flexion, or extension.The closest condition listed in Table 17-33 would be “trochanteric bursitis (chronic) with abnormal gait,” assuming the patient's gait became abnormal with prolonged walking due to the onset of pain and weakness. This diagnosis is associated with 3% whole person (7% lower extremity) impairment. A rating physician who found the patient's residual complaints credible might justify use of this proxy diagnosis based on clinical judgment. A conservative evaluator, following the fifth edition as written, would likely find no impairment based on the normal physical examination. Other than in the state of California, it is rare for additional impairment to be assigned for pain.However, the updated and improved current (sixth) edition of the AMA Guides does provide a means to rate this injury. Using Table 16-4, Hip Regional Grid (6th ed, 512), and the diagnoses of “strain, tendonitis, or h/o ruptured tendon,” the patient would have 0% lower extremity impairment (LEI) if there were “no significant objective abnormal findings of muscle or tendon injury at MMI,” a default 1% LEI for “palpatory and/or radiographic findings,” and a default 5% LEI for “moderate motion deficits and/or significant weakness.” Given the normal physical examination, a rating physician could justify a 0% rating because there were “no significant objective abnormal findings of…tendon injury” at MMI. However, the patient had, and may still have, imaging findings (ie, MRI) consistent with his diagnosis. If one concluded the ongoing complaints were credible and probably due to residual abnormality in the tendon that would be apparent were a repeat MRI obtained, he falls into class 1.Assuming the latter scenario, regarding functional history adjustment from Table 16-6 on page 516, grade modifier 1 is appropriate given his limited walking endurance. Absent any abnormality at MMI, physical examination adjustment using Table 16-7 on page 517 results in grade modifier 0. Clinical studies adjustment using Table 16-8 on page 519 is not indicated because MRI results were used to select the class. Inserting the grade modifier functional history (GMFH), grade modifier physical examination (GMPE), and class of diagnosis (CDX) into the net adjustment formula yields: (GMFH-CDX) + (GMPE-CDX) = (1-1) + (0-1) = 0 + −1= −1. Hence, the net adjustment is –1 and final grade is B, which is also 1% LEI. This can be converted to 1% whole person impairment (WPI).In summary, if limited to using the fifth edition, and employing a proxy diagnosis, the patient has 7% LEI or 3% WPI. However, strict adherence to the fifth edition or doubt about the credibility of his residual symptoms could justify a 0% impairment rating. If one wishes to rate the correct diagnosis and use of the sixth edition is permissible when the fifth edition is lacking, ratings of either 0% or 1% LEI and WPI could be justified, again depending on clinical judgment regarding symptom validity.